pH Dropping Every Day in DWC (Lucas Formula) ??IS THIS NORMAL?? Help!!!

Discussion in 'Hydroponic Growing' started by steakandshake, Mar 14, 2012.

  1. #1 steakandshake, Mar 14, 2012
    Last edited: Mar 15, 2012
    Okay my plants all together are 2.5ft tall and 3.5x3.5ft wide. Their in a 18 gallon rubbermaid reservoir which is holding ~15gallons of solution, and I have 5 plants. I am in my 1st week of flowering , running an indica dominant strain.

    Is it perfectly acceptable and normal for your pH to lower by nearly a .15 point every day?(edited) My ppm is staying relatively the same. (it is ~850ppm)

    I have to add quite a bit of pH up every day to bring it from ~5.7 to ~5.85ph

    Please help! Appreciate it like crazy
  2. 5.7 to 5.85? Do you mean 4.7 to 5.85? If it's the first then you have no problems.

    If your ppm is staying the same, or rising and the pH is dropping then you're giving them too much nutes. You want your pH to rise slightly, and ppm slowly drop.

    Is your ppm at 0.5 conversion? Maybe you're following directions for a 0.7 meter with a 0.5.

    Add a liter of water or so, then take the ppm - lower it by 50-100. Then drain a liter of mix out. Tomorrow, do it again if the pH is still dropping.
  3. #3 steakandshake, Mar 15, 2012
    Last edited: Mar 15, 2012
    Sorry it wasnt a full 1.0 point of pH, I meant .1 to .15 points, just edited it, it goes from 5.85pH down to 5.7pH in 24 hours

    I am using the 0.5 conversion.

    And my ppm does stay relatively the same, it seems to fluctuate between the same +/- 25ppm every day (from 715ppm to 740ppm)

    So ppm staying the same means too much nutes? ~725ppm doesnt seem like it would be too high, in fact I was kind of thinking it was a tiny bit too low for where the plants are at? (2.5ft tall, 3.5x3.5ft wide and in week 1 of flowering)

    Also, earlier, when I was vegging, and in the first few days of 12/12 light, my pH was slowly rising as you say it should be doing, but then about two to three days ago the pH began to drop instead of rise, idk if this information can help anyone help me

    Really appreciate the help s7exiled, and anyone else who wants to help

    P.S. - s7exiled I think I understand what your trying to tell me, so you think my ppm is too high, and thats causing the pH to drop? So by diluting the soup with pure RO water and lowering the ppm, this will fix the pH problem? I have always had relatively the same ppm in my soup, because im using the Lucas Formula, which states you use the same concentration of nutes throughout the whole grow., I simply top off my reservoir with 100% nute solution every day, could that still be the issue even though im using lucas formula?
  4. Another thought ( sorry to jump threads ) but when are you taking your readings? After your lights first come on your ph could be lower because plants will actually release some nutrients during the dark cycle but then suck them back up during the light cycle and your ph would rise up some again by the middle to end of the day. Also in the first week you will not see drastic bud production but as long as you are seeing growth you are good.
  5. I take my reading on average after about 2.5-3.5 hours of the lights being on.

    I am not seeing drastic bud production, slow pistil growth is occuring though, and as I said just a second ago in my other thread, I wasnt using my exhaust fan at night in my growtent, which was making the air quite stagnant, I hope this was one of the reasons for the slower growth, and not my pH issues (pH dropping slowly instead of rising slowly like its supposed to)
  6. #6 s7exiled, Mar 15, 2012
    Last edited by a moderator: Mar 15, 2012
    Honestly, depending on your res size that fluctuation is really good. You want it to range anyway, 5.5-5.8 (some say up to 6.1). Yours is pretty stable, lots of people need to pH whole points down every day.

    What are you using to pH up?
    What's the conversion of your ppm meter?

    If your plants are responding to the 725ppm well, and they're not stunted/drooping/clawing problems then leave it. Just check every day if you really want to have it at a precise value and add probably just add the couple of drops to pH it up

    If not, lower the ppm 50 each day until the balance of pH/ppm is reached



    You should aim 5.85-6 during flower
  7. #7 steakandshake, Mar 15, 2012
    Last edited: Mar 15, 2012
    Ive got a 18 gallon res which holds about 14.5 gallons of solution

    Im using general hydroponics liquid pH up and pH down

    My meter is NaCl .5 conversion

    I have to add a lot more than a couple drops to pH it up though, it takes ~20-25 drops for it to go from 5.7 to 5.85, is this normal? My water is mostly RO water with like 3ppm

    As far as I can tell the plants look good, except for the slow budding (flowering) Dont have any drooping or clawing

    Edit- could this possibly be caused by the plants being in flowering and not vegetating?
  8. All good comments here...:)
    Just wanted to add that your ph may be lowering from evaporation.

    To raise the ph instead of using ph up, potassium silicate(protek)helps and your adding something beneficial the mix...;)
  9. #9 steakandshake, Mar 15, 2012
    Last edited: Mar 15, 2012
    Hmm evaporation? My tub is fairly well sealed, wouldnt my ppm go up if my water was evaporating?

    I need some more closure on this lol, is pH dropping like this normal? Drop of .15 to .2 points a day, and ppm stays the same.

    I have to know if im doing something wrong this is driving me batty ! lol

    Heres some more information about my grow:

    soup temps of 63-68*F
    air temps of 68-78* F
    humidity of ~45%
  10. You want the pH to rise just a little (5.85 to 5.95 for example) instead, but that's a pretty small fluctuation - so if the plants look fine you can leave it.

    If the leaves look excessively green and you think there is slow growth - you can try what I said. Add pH'd R/O water until you have 50ppm lower or even 25, then drain out the same amount of water you added - so the soup water level will be the same.

    Try to pH your res at 5.95 and see if that boosts pre-flower growth
  11. Well your nutes would be concentrated in a less volume of water lowering the ph...

    I agree with the fluctuation being ok...Just part of the game with hydro...
  12. Ok so I definitely have a problem then if my pH is falling at all, even a little bit? This is not supposed to happen at all right?

    The leaves do not look excessively green i dont think, they arent glossy green like a nitrogen overdose is.

    Has ANYONE ever had this occur to them in a DWC hydro grow? pH dropping a bit like this every day?

    I will try to dilute my reservoir tomorrow like you said and see if that helps, i honestly was thinking i didnt have ENOUGH nutes though and that that may have been causing my pH dropping, because my plants are too big and dont have enough nutrients from the 100% lucas formula? But IDK
  13. #13 colafarmer, Mar 15, 2012
    Last edited by a moderator: Mar 15, 2012
    Curious if you have recirculating or, drain to waste system...

    Edit...Never mind seen it's DWC
  14. Just a part of the game? Even if its fluctuating down and not up? (i thought pH rising was normal and pH falling was abnormal)

    I see what you mean how that would lower the pH. I still find it kind of hard to believe that these big bushy plants I have are being overfed by a measly ~730ppm of nutes (@ .5 conversion factor) But I am still very much a newbie to hydroponics and have little experience with hydro.

    So all in all everyone agrees that I should dilute my reservoir by 25-50 ppm to see if that will stop my pH from falling? Because my plants are consuming more pure water than they are nutrients?

    (sorry if I am too thorough with trying to make sure I understand everything, I am a stoner you know)

    Thank you everyone !
  15. Well it shows your plants are drinking more water than they're uptaking nutrient. You're going to have a fluctuation, and those are basically the two sides.

    pH rising, ppm dropping = too little nutes
    pH dropping, ppm rising = too much

    Not every plant can handle the 950~ ppm lucas formula, you just need to go by what your plants are wanting
  16. I have a simple DWC rubbermaid container, I guess that would be recirculating??? I dont know the difference between recirc and drain to waste. I just have a reservoir with air stones on the bottom, and an air pump pumping through those stones.

    I am using the 100% nutrient solution top off method, where I just top off the res every day with 100% solution (lucas formula)
  17. #17 steakandshake, Mar 15, 2012
    Last edited: Mar 15, 2012
    Okay I made a mistake, my TDS meter was not calibrated right, I always shook it down to get the excess water off of it before storing it, and shaking it down was making it inaccurate (its a cheap meter). After re-calibration, my reservoir ppm is actually 853ppm.

    My pH meter is fine though, its calibrated correctly.

    pH'd my reservoir to 5.87, and its ppm is 853, going to recheck it tmrw morning and see how those numbers change, and from there I will probably add pure RO water to dilute and hopefully equal out my system.

    So when my system is optimally dialed in, what should my ppm and pH be doing every day? i.e. one rises one falls, they both stay same, or what?

    also my night temperatures (lights off) could reach as low as 60* F perhaps, no lower though, this isnt a problem, right?
  18. Yeah you've got a recirculating dwc

    When it's dialed in, the ppm should slowly drop and in tandem the pH rises. Then like you said before, you add back to maintain the ppm/pH level.

    60F is fairly low, I'd probably get any potassium silicate product to prevent any slowing of growth (increases resistance to hot or cold temps). 60F is even a *little* too low for the res, you should try and get that to like 62-65F and the air in the cab around 65F.
    A heater on a repeat cycle timer maybe?

    You should check the res temps if you haven't, because let's say the temp in your res rises while the lights are on - the night would cool off the res to the ideal temperature.
  19. Yea, temps do play a role in ph and along with the composition of the solution can cause a chemical reaction fluctuating the ph....

    I agree with s7exiled and would make res temperature a priority and do whatever it takes to maintaining optimal hydro conditions.

    Adjusting EC,PH etc are a common daily task we must do with hydro, but the more optimal the rest of your system(flushing, cleaning etc,) the less fluctuation you will endure.
  20. #20 steakandshake, Mar 15, 2012
    Last edited: Mar 15, 2012
    Okay I checked my temps last night and they dont drop all the way to 60*, its more like 62-65 as you said, so I think that is good in that aspect.

    Just checked ph and ppm, pH dropped .09pH in 20 hours, and the ppm basically stayed the same.

    My strain is Cole Train, and apparently it is a heavy feeder, a nutrient hog according to the seedbank.

    I have yet to top off this morning, I am in a state of debate i dont know if I should add more nutrients or do what you said and dilute the nutrients at this point.

    edit: it appears I have some fan leaf stems that are turning reddish, mostly on the top of my plant, what could this be from? a deficiency?

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